JPS6264792A - Cooling liquid supply device for superconducting magnetic field generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a low temperature maintenance device for equipment that requires extremely low temperature maintenance, such as a superconducting magnetic field generator.

Conventional technology In superconducting magnetic field generators, such as NMR imaging equipment, liquid nitrogen, which is conventionally used to keep liquid helium used to cool coils, is manually refilled into a liquid nitrogen container about twice a month. In terms of workability, it is necessary to: 1. It is necessary to transport the liquid nitrogen container for the auxiliary line by hand, and to secure a passage for it.

2. A strong magnetic field is generated near the superconducting magnetic field generator, so if the replenishment container contains magnetic material, there is a risk that the container will be attracted to the superconducting magnetic field generator. .

3. It is necessary to periodically check the amount of liquid nitrogen in the liquid nitrogen container for cold storage.

It had the following drawbacks.

C. Problems to be solved by the proposed method In the super-conducting magnetic field generator, the liquid nitrogen in the liquid nitrogen container for cold storage evaporates and loses its weight, so it is necessary to check the remaining liquid nitrogen in the container. It was necessary to carry out supplies manually.

The present invention improves the safety of the superconducting magnetic field generator by automating the replenishment of liquid nitrogen for cold storage in the device.
The purpose is to facilitate the maintenance and management of cold storage capacity.

20 Means for Solving Problems The present invention provides a superconducting magnetic field generator in which a replenishment liquid nitrogen container for storing liquid nitrogen to be replenished to a cold storage liquid nitrogen container is fixedly installed, The liquid nitrogen containers are connected by a liquid nitrogen transport pipe, and the pipe is equipped with a motor that can adjust the flow rate at the outflow port from the replenishment liquid nitrogen container and at the inlet port to the cold storage liquid nitrogen container. An automatic gas venting valve is installed at the control valve and gas venting port for discharging the gas in the pipe, and a signal from the liquid level detection device that detects the amount of liquid nitrogen in the cold storage liquid nitrogen container indicates that the liquid level is detected. When the liquid level reaches a certain level, the liquid nitrogen supply starts, and when the liquid level reaches a certain level, the replenishment is stopped. Automatically transfers liquid nitrogen into a container.

Po 0 action When the liquid level in the cold storage liquid nitrogen container drops below a certain point, the liquid level detection device is activated and the leakage from the replenishment liquid nitrogen container side is detected.
When valve 1 gradually opens and the pressurizing device is activated, liquid nitrogen slowly fills the pipe, and when the pipe is filled with liquid nitrogen up to the gas vent in the center of the pipe, the pipe is normally open. -The upper gas vent is closed, and the inlet valve on the side of the cold storage liquid nitrogen container, which is normally open, is opened.
Liquid nitrogen flows into the cold storage liquid nitrogen container. When liquid nitrogen flows into the cold storage liquid nitrogen container up to the liquid level, the liquid level detection device activates and closes all valves, automatically replenishing the cold storage liquid nitrogen container with liquid nitrogen and To improve the safety of the conductive magnetic field generator and to facilitate the maintenance and management of the cold storage capacity.

Embodiment In FIG. 1, I is a superconducting magnet main body, 2 is a cooling liquid helium container for cooling the superconducting magnet main body,
3 is a cold storage liquid nitrogen container that keeps the cooling liquid helium container 2 cold; 4.4' and 4'' are double walls for heat insulation to cut off heat conduction between the containers, and 5 is a storage liquid nitrogen container for cold storage. A liquid nitrogen container for replenishment, 6 a liquid level detection device for detecting the liquid level of liquid nitrogen in the cold storage liquid nitrogen container 3, 7 a liquid level detection device 6
a control device that controls each valve using signals obtained from the 8.
9.10 is a control valve with a motor, 11 is a pressure regulating valve, ]2
is an automatic gas vent valve with a structure as shown in Figure 2. When gas flows in from below, the ball inside is at the position indicated by the dotted line, but when liquid flows in, the ball rises due to buoyancy. This is an automatic gas vent valve with a structure in which the ball presses against the upper valve seat to stop liquid from flowing out. 13 is a pipe for transporting liquid nitrogen, 14 is a pressure sensor, 15 is a pressure gauge, and 16 is a helium gas cylinder for increasing the pressure in the liquid nitrogen container 5 for replenishment.

Next, the operation of the -F description device will be explained. Fig. 3 is a flowchart of the operation. First, valves 8°9 and 10 in Fig. 1 are normally open, and when the liquid level of liquid nitrogen in the cold storage liquid nitrogen container 3 falls below point E, the liquid level opens. From the detection device 6 to the control device 7
A signal is sent to the controller 7, which gradually opens the valves 11 and 8 (a), and liquid nitrogen is gradually sent to the transportation pipe 13. Initially, the liquid nitrogen is at the outside temperature in the pipe 13. Therefore, the generated gas is rapidly vaporized and is discharged through the automatic gas vent valve 12 since the valve 9 is closed.

When the pipe 13 is sufficiently cooled by vaporization of liquid nitrogen,
The liquid nitrogen stops vaporizing, and when the pipe 13 is filled with liquid nitrogen and the automatic gas vent valve 12 is full, the automatic gas vent valve 12 has the structure shown in Fig. 2, so it closes automatically, allowing the replenishment. When the pressure inside the liquid nitrogen container 5 rises and reaches the specified pressure (b), a signal is sent from the pressure sensor 14 to the control device 7, which opens the valve 9 (c), and the liquid nitrogen is released. The liquid nitrogen begins to flow into the cold storage liquid nitrogen container 3.

When the pressure inside the cold storage liquid nitrogen container 3 increases due to the inflow of liquid nitrogen, the gas is automatically discharged by the pressure regulating valve 11, and when the liquid nitrogen is filled up to point F (d), the liquid level detection device 6 A signal is sent to the control device 7, and the control device 7
NJ: Valve 8, valve 9, and valve 10 are closed (e), and the replenishment of liquid nitrogen is completed. The liquid level detection means utilizes a change in resistance due to temperature of a semiconductor resistance element, and uses a change in electrical resistance f+fi caused by a change in temperature of a measurement terminal when the liquid level reaches the measurement terminal.

G. Effects According to the present invention, since liquid nitrogen can be automatically replenished into a liquid nitrogen container for cold storage, safety when replenishing liquid nitrogen as a cold storage liquid in a superconducting magnetic field generator and the superconducting magnetic field generator can be improved. This makes it possible to increase labor savings in maintenance and management of cold storage capacity.

[Brief explanation of drawings]

FIG. 1 is a side view of one embodiment of the present invention, FIG. 2 is a detailed view of the automatic gas vent valve 12, and FIG. 3 is an explanatory diagram of the operation of the control device. Agent: Patent Attorney Kosuke Agata = 7- Su Tatami

Claims (1)

[Claims] In a superconducting magnetic field generator, a liquid level detection device that detects the liquid level is installed inside the cold storage liquid nitrogen container, which is the cold storage outer cylinder of the liquid helium container that cools the superconducting coil for magnetic field generation. A liquid nitrogen container for replenishment is fixedly installed, and a pipe for transferring liquid nitrogen is connected between the liquid nitrogen container for replenishment and the liquid nitrogen container for cold storage, and a gas vent valve for discharging the gas in the pipe is installed at the top of the pipe. A control valve is installed at both ends of the pipe, and when the liquid level falls below a certain level based on a signal from the liquid level detection device, the supply of liquid nitrogen is started, and when the liquid level reaches a certain position, A cooling liquid replenishing device in a superconducting magnetic field generator, comprising a control device that controls the control valve to stop replenishment.